I am about to start the mods on my 90 5.0L RS, and I want to start with a K&N 14x3 open element airclean. I know that I want to get a drop base but I dont know what kind i should get, the one that drops 1.25" below a carb. flange or the one that drop 13/16" below the flange, or does it matter.

1990 5.0L RS
future mods:
14x3 K&N open aircleaner
Hooker shortie super comp. headers
Catco Converter
Flowmaster Cat-back exhaust
Richmond 3.73 Gears
(Hopefully all this summer)